With wide application of intelligent terminals, people have a growing requirement for data network traffic. To meet people's increasing network requirements and improve system performance, systems and standards of wireless local area networks (Wireless Local Area Networks, WLANs) experience multiple evolutions. For example, in a Wi-Fi system, a standard of the Wi-Fi system sequentially evolves from Institute of Electrical and Electronics Engineers (IEEE) 802.11a/b to IEEE 802.11g, IEEE 802.11n, and even to IEEE 802.11ac.
In the 802.11n standard, two physical-layer frame formats are defined for a data packet: an HT mixed format and an HT Greenfield (Greenfield) format. In the 802.11ac standard, a very high throughput (VHT) format is defined. A signaling field of a data packet with legacy format uses a binary phase shift keying (BPSK) modulation scheme, a signaling field of a high throughput data packet uses a quadtrature BPSK (QBPSK) modulation scheme, and a signaling field of a very high throughput data packet uses BPSK and QBPSK modulation schemes.
Currently, the IEEE 802.11 Working Group has further founded a High Efficiency Wireless Local Area Network Study Group (High Efficiency WLAN Study Group, HEW SG). An objective of the High Efficiency Wireless Local Area Network Study Group is to construct a next-generation wireless local area network to increase spectral frequency and further improve a system throughput and a regional throughput, so as to provide a better service for users. The High Efficiency Wireless Local Area Network Study Group has introduced a data packet in a new format, that is, a data packet in a HEW format.
When transmitting a data packet, a transmit end modulates information (for example, pilot information and signaling information) carried in the data packet. A receive end may detect information that uses different modulation schemes, so as to determine a corresponding format of the data packet.